This invention relates to apparatuses by which pipes different in diameters are fitted or nested one inside another, beginning with one largest in diameter, into multiple pipes, or the multiple pipes are denested successively beginning with one smallest in diameter, in order to remarkably improve the transportation efficiency of pipes, and more particularly to a pipe nesting and denesting apparatus in which the axis of a pipe smaller in diameter which is to be nested or denested by a supporting rod fixedly mounted on a carriage is correctly aligned with the axis of a pipe larger in diameter which receives the pipe smaller in diameter, whereby the pipes are nested or denested in a period of time which is about a half or less of the period of time required for a conventional nesting and denesting apparatus.
In shipping a number of pipes such as steel pipes, cast iron pipes or asbestos pipe, they are coaxially fitted (or nested) one inside another in advance. In unloading the pipes from boats or at truck terminals, they are denested, and only pipes having diameters requested are transported to the respective working site. This is undoubtedly economical and effective in transportation efficiency.
A pipe nesting apparatus has been known in the art for a long time. In a typical example of the conventional pipe nesting apparatus, a horizontal supporting rod for supporting a pipe is provided on a carriage on rails in such a manner that its height is adjustable as desired, a V-shaped receiving stand for receiving a pipe in the axial direction of the rails from and delivering to a fork lift is disposed between the rails at a position forwardly of the carriage in such a manner that it can be retracted from the rails when required, and a V-shaped nesting stand is fixedly mounted on the rails in front of the receiving stand. The carriage is run toward the pipe on the receiving stand while the supporting rod is being adjustably moved up or down by an operating stand provided on the side wall of the carriage, so that the supporting rod is inserted into the pipe on the receiving stand. Thereafter, the supporting rod is lifted to support the pipe. Then, the receiving stand is retracted from the rails to place it on the V-shaped nesting stand. This operated is repeatedly carried out to nesting pipes one inside another to obtain multiple pipes.
Spacers are inserted between the multiple pipes thus obtained so that they may not be damaged by vibrations or impacts or cargo crumbling which may occur during the transportation. In general, the spacers are fixedly inserted into the pipes manually after being fixedly secured to a belt at equal intervals, during the nesting operation. Therefore, in the multiple pipes, the axes of the outermost pipe and the remaining pipes which have been inserted one inside another, i.e. the axes of the pipes are not always in alignment with one another, and at worst the axes of the pipes are gradually deviated from one another.
With the above-described pipe nesting apparatus, it is extremely difficult to correctly adjust the axis of the outermost pipe. Therefore, in nesting two pipes for instance, one of the pipes must be loosely fitted inside the other; that is, in the operation, the difference in radius between the two pipes must be more than 100 mm. Thus, the number of pipes to be nested is limited. In association with this, bulky spacers of the order of 98 to 100 mm in thickness must be employed.
In addition, with the conventional apparatus, while a pipe smaller in diameter is inserted into a pipe larger in diameter, the end of the former may be struck against the inner wall of the latter to peel off the corrosionresisting coating, or the former may fatally damage the latter to the extend that the latter cannot be used. In the latter case, it may be impossible to insert the smaller diameter pipe into the larger diameter pipe, and accordingly it may be necessary to repeat the nesting operation all over again by retracting the carriage with the pipe.
Furthermore, in denesting the multiple pipes beginning with the innermost pipe, it takes a relatively long time, great skill and intricate steps to pull out the innermost pipe, because a method is not employed in which the axis of the pipe on the nesting stand is made in alignment with the axis of the supporting rod.